Gigantic Sunspot Unleashes Flare; Expect Aurorae Tonight!

Gigantic Sunspot Unleashes Flare; Expect Aurorae Tonight!

The sunspot cluster AR1944 blasted out a moderately strong solar flare yesterday, and we may get aurorae tonight.

Photo by NASA/ESA/SDO/Helioviewer.org

Right now, the Sun is sporting a huge sunspot called AR1944. It’s grown in size over the past few days to a staggering 200,000 kilometers (125,000 miles) across. As I wrote the other day, sunspots are regions of intense magnetism, and these magnetic fields store huge energies. They can be unleashed in vast explosions called solar flares … and AR1944 popped off a good one on Jan. 7. The image above shows the Sun in ultraviolet by NASA’s Solar Dynamics Observatory, taken on Jan. 7 at 18:33 UTC, just after the flare exploded. The bright white patch? Yeah, that’s it.

The flare was a class X1, which is pretty strong. It also triggered a coronal mass ejection, an eruption of subatomic particles, toward the Earth. There’s no need to panic; these happen relatively often. This one was pretty fast, with a speed of about 2,000 kilometers per second—that’s 4.5 million miles per hour!

I took this photo on Jan. 8 at about 17:00 UTC, and you can easily see AR1944. The biggest sunspot in the cluster is now 15 times the width of our entire planet.

Photo by Phil Plait

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It’s expected to hit the Earth’s magnetic field sometime today or tonight. The Space Weather Prediction Center says it may interact strongly with our geomagnetic field, producing aurorae. I’ve seen some folks predicting even mid-latitudes may see the lights, so I urge folks to go out after dark and look north. Unfortunately the Moon is half-full and so the sky will be a bit bright. It sets just after midnight local time, so if you go out later your chances of seeing the aurora might be better. It looks like we’ll have clear skies here in Boulder, Colo., so I’ll be taking a peek. Aurorae may still be visible Thursday night as well.